7182500 OCSP revocation checking fails if OCSP response does not contain certificates

[Vincent Ryan]

Hello,

Please review the following changeset for JDK 7u6:
     http://cr.openjdk.java.net/~vinnie/7182500/

The bug report is at:
     http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7182500

The error occurs when an OCSP responder opts not to return the signing
certificate used in an OCSP response. The fix is to set the default
signer cert to be the cert of the issuer of the cert being validated.

This fix addresses a regression in the OCSP client which was introduced
in my fix for CR 7168191
(http://hg.openjdk.java.net/jdk7u/jdk7u6-dev/jdk/rev/52ab0f489dab).

Thanks.